NameError: name 'slicer' is not defined

Windows 10, Slicer 5.0.2, jupyter server 5.0

NameError: name ‘slicer’ is not defined

Please refer to this screenshot: Capture — ImgBB

In the cmd history, we can see that the scene file is loaded successfully, however, I always failed to call the slicer.util.getNode command.

This code works well in version Slicer 4.13, and the error appears in version 5.02.